Method for producing uranium and uranium-zinc alloys



Patented, Sept. 24, 1929 UNITED STATES PATENT time JOHN WESLEY MABDEN, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO WESTING- HOUSE LAMP COMPANY, A CORPORATION OI PENNSYLVANIA METHOD FOR IRODUCING URANIUM AND URANIUM-ZINC ALLOYS Ho Drawing.

This invention relates to the preparation of rare metals and more particularly relates to the preparation of the highly'reactive rare refractory metals, such as uranium, thorium and the like in an alloyed form substantially inert with respect to the deleterious atmospheric gases but capable of being subsequent- 1y heat treated in vacuo to recover the said refractory-metal therefrom in a fused coherent form capable of being mechanicall deformed to wire, filament, sheet and the e.

.This invention is a continuation-in-part of a copending application Serial No. 91,620, entitled Method for producing uranium and uranium zinc alloy, filed March 1, 1926, and' assigned to the same assignee as the present application.

In this copending application is described a process for formin a powder form of a uranium zinc alloy su stantially resistant to the atmospheric gases and which may subsequently be compacted and heated in vacuo to distil the zinc therefrom, leaving behind a substantially pure oxide free fused uranium metal product. V

The original specification of said applica- 7 tion, on page 4, lines 5-32 inclusive contained reference to another method of forming a uranium zinc alloy in a'substantially fused 3o coherent form from which the uranium could be obtained by distilling away the-zinc in vacuo. This method substantially as disclosed in the original application was withdrawn at the request of the examiner to form the basis of a division application.

The method as described in said copending application of which this is a continuationin-part stated: The other method of preservinlgltlhg uranium or oiizher rare metal} iron;

40 tarnis consists in ormmg' an a 0y 0 the metal with zinc and other metals.

' In copfndig' ,g ap lication Serial No. 504,154, ed eptem r 29, 1921, entitled Method for the preparation of rare metals and alloys thereof, and assi ed to the present assignee, there is descri a process of alloying the rare metals with another metal, for example, aluminum,'the object being to form a stable product which may be readily handled in the ainwithout danger of oxidathe zinc alloy formed is dissociated t Application filed August 29, 1928. Serial No. 302,884.

tion. If desired, the rare metal may be recovered by volatilizing the aluminum under suitable heat treatment conditions.

I have found that although this method is satisfactory for the indicated purpose, dif- 5 ficulty may be encountered in removing the aluminum although thismay be readily done if the proper conditions are observed. In forming an alloy of zinc and uranium for example, I proceed in part as described in 00 copending application Serial No. 618,544, filed Feb.- 12, 1923 and entitled Method of preparing refractory metals, and assigned to the same assignee as the present application. 7 .65

The process as set forth in said application is followed with the exception that there is added to the mixture or charge of raremetal oxide, calcium and calcium chloride, a suitable quantity of zinc. The zinc, during the reaction in the hermetically sealed container is highly heated and combines with the rare metal to form an alloy. However, ifthe temperature of the reaction is suflicientl high,

hrough the volatilization of the zinc from the alloy, thus' leaving the rare metal behind in coher-ent form.

The particular character of the alloy formed by this method depends. actually upon the amount of zinc added to the reducingcharge as the melting point ofthe zinc is relatively low and during the reducin reaction there is maintained by means 0 exterior heating on the sealed'container containing the reducing charge, a temperature approximating 900 to 950 C., itis obviousthat a wide range of permissible alloys may be obtained.

It is preferable, owing to the high fusion point of the uranium to utilize a relatively large excess of zinc which thereafter fuses and forms a regulus of metal in the bottom of the container. Upon removal from the container this regulus of metal is recovered 95, by any desirable method and placed into a suit-able furnace and the zinc contentthereof distilled away by heating in vacuo or an inert environment and the uranium metal remaining heated to fpsion.

Grams..

Calcium chloride (dried and ground to 20 mesh) 200 Calcium (chips 4; x A x 120 Uranium oxide (U C. P. powder 270 Zinc dust C. P. grade 130 This charge provides for an amount of zinc approximately equal to two molecular weights for every molecular weight of ura- ,nium metal produced by the reduction reaction. Other proportions may be employed but I have found that this proportion is most desirable on a commercial basis.

.If desired, a proportion of zinc chloride or other compound of relatively low heat of formation, the metal component of which would be non-contaminative with respect to the uranium zinc alloy formed, may be utilized to increase the heat energy of the reaction to ensure reduction of the U0 and to supply suflicienttemperature to assist in the alloy formation.

This char e is placed in the receptacle or bomb as disc osed in said copending application suitably sealed from the atmosphere and heated by externally applied heat to the reaction temperature. Subsequently the temperature of the reduction bomb is maintained at 900 C. to 950 C. for from 1 to 3 hours, depending upon the particular charge employed. Upon cooling to room temperature, the bomb may be opened, the metal regulus which may be found occasionally in the form of beads or coarse powder, may be separated by suitable lixiviation means from the calcium chloride and calcium oxide of the reduction reaction. The metal alloy product may then be dried, placed in a suitable container, such as alundum, magnesia or thoria crucibles and heated by induction in vacuo or an inert environment to distil away the zinc content.

As above mentioned, the copending application Serial No. 504,154, filed Sept. 29, 1921, v

contemplated the forming of an aluminum alloy with the rare refractory metals and subsequently vaporizing away the aluminum. It is found, however, that it is extremely diflicult to boil away the last traces of the aluminum, even in a high vacuo whereas with the present method the zinc is readily and effectively removed by such a distillation process.

By the present invention, the uranium zinc alloy may be proportioned so that the same will be sufficiently brittle to be easily-ground to a powder in a mort'er so that the same may then be suitably compacted to any desired shape. Thereafter it may be incorporated in a vacuum furnace and heated by induced eddy currents to volatilize the zinc. However, it is not essential to grind to small sizes and compact before heating to volatilize the zinc. The shrinkage will be found, during heating. to be quite large depending upon the amount of zinc present and no definite melting point is apparently reached until the. substantiallv pure uranium is obtained.

In the presence of appreciable amounts of iron, a lower melting point alloy may be obtained and such additional intcrmetallic impurities must be avoided.

In the absence of such-contaminating impurities, the zinc content of the alloy may be entirely distilled away and the remaining uranium product when fused, will be found to be substantially pure and capable of being mechanically deformed by cold working means into wire, sheet, filament and the like forms, useful in the arts. This has heretofore been diflicult to obtain by prior processes due to the extreme chemical activity of the metal in the powder or even coarsely granular powder form which caused the metal to absorb large quantities of atmospheric impurities during the period of transmission from the reducing chamber to the fusing or sintering chamber. By forming an alloy of the metal with zinc as by my process I am enabled to substantially prevent atmospheric corrosion or contamination. Moreover, the presence of the zinc therein prevents the absorption of deleterious gaseous impurities therein from the residual gases of the vacuum device or inert environment employed in the sintering process and vaporizing of the zinc from the alloy.

Although the intention has been described and a specific example given, it is apparent that many variations in the process may be made without departing essentially from the nature of the invention as may be encompassed in the following claims.

What is claimed is:

1. The method of producing a rare refractory metal alloy which comprises reducing a compound of the rare metal and simultaneously alloying therewith a proportion of Zinc.

2. The method of alloying a rare metal with a metal of low volatility which comprises incorporating in an hermetically sealed container, a compound containing the rare metal, a reducing agent, a fluxing agent and a sufficient desired proportion of said metal of low volatility and thereafter effecting the reduction and alloying thereof by heating to elevated temperatures.

3. The method of preparing a uranium zinc alloy which comprises heating a mixture containing a compound'of uranium, a reducing agent, a fluxing agent and zinc in an hermetically sealed container and then recovering the alloy. I

4:. The method of preparing a uraniumzinc alloy which comprisesheating a mixture thereto and zinc and then recovering the uranium zinc alloy.

5. The method of preparing a uranium zinc alloy which comprises heating uranium oxide,

-5 calcium, calcium chloride and zinc in an hermetically sealed container, recovering the rare metal alloy by removing the salts of the reaction by means of suitable solvents.

6. The method of producing uranium which comprises forming an alloy thereof with zinc by reducing a compound of uranium in the presence of zinc in an hermetically sealed container, and thereafter thermically decomposing the alloy.

7 The method of producing uranium which comprises forming an alloy thereof by reducing an ogidgof uranium by means of calcium and an alkaline halide flux in the presence of zinc, the reaction taking place in anhermetically sealed containef'' y 8. The method of preparing uraniu r'ifwhich-\ comprises forming an alloy thereof with zinc and subsequently recovering the metal by volatilizing the zinc in vacuo.

9. The method of preparing a rare metal which comprises alloying the same with zinc and subsequently recovering the rare metal by distilling the zinc therefrom in an inert environment.

10. The method of preparing a rare metal which comprises forming an alloy thereof with zinc by reducing a compound of the rare metal in the presence of zin and subsequently recovering the rare meta from the alloy thus formed by distilling the zinc therefrom.

11. The method of preparing uranium which comprises forming an alloy of uranium with zinc by reducing a compound of uranium in the presence of zinc, and then subsequently recovering the uranium by distilling the zinc from the alloy.

In testimony whereof, I have hereunto subscribed my name this 28th day of August 1928.

JOHN WESLEY MARDEN. 

